Recently, as electronic devices are miniaturized and further improved in performance, printed wiring boards having a wiring pitch narrowed, i.e., high-density wiring are desired. As a method of mounting a semiconductor for achieving high-density wiring, instead of the conventional wire bonding method, a flip chip bonding method is widely used. The flip chip bonding method is a method in which a wiring board and a semiconductor are bonded together using a solder ball instead of a wire. A solder ball is disposed between a wiring board and a semiconductor opposite to each other, and the whole of them are heated to cause reflow of the solder (melt bonding), thus bonding and mounting the semiconductor onto the wiring board. In this method, heat at approximately 300° C. is applied to the wiring board and others during the solder reflow. In this instance, the wiring board formed using a conventional resin composition as a material possibly suffers heat shrinkage to apply large stresses to the solder ball bonding the wiring board and semiconductor, causing a bonding failure of the wiring.
[Patent document 1] Japanese Unexamined Patent Publication No. 2004-182851
[Patent document 2] Japanese Patent No. 2740990
[Patent document 3] Japanese Unexamined Patent Publication No. 2000-243864
[Patent document 4] Japanese Unexamined Patent Publication No. 2000-114727